Curable liquids and inks for toys and food packaging applications

Abstract

A free radical curable liquid for inkjet printing of food packaging materials includes no initiator or otherwise one or more initiators selected from the group consisting of non-polymeric di- or multifunctional initiators, oligomeric initiators, polymeric initiators, and polymerizable initiators; wherein the polymerizable composition of the liquid consists of: a) 25-100 wt % of one or more polymerizable compounds A having at least one acrylate group G1 and at least one second ethylenically unsaturated polymerizable functional group G2 different from the group G1; b) 0-55 wt % of one or more polymerizable compounds B selected from the group consisting of monofunctional acrylates and difunctional acrylates; and c) 0-55 wt % of one or more polymerizable compounds C selected from the group consisting of trifunctional acrylates, tetrafunctional acrylates, pentafunctional acrylates and hexafunctional acrylates.

What is claimed is: 
     
       1. A free radical curable liquid for use in printing, the free radical curable liquid comprising:
 one or more initiators selected from the group consisting of polymeric initiators and polymerizable initiators; 
 a polymerizable co-initiator and/or a polymerizable inhibitor; and 
 a polymerizable composition consisting essentially of: 
 25-98 wt % of one or more polymerizable compounds A including at least one acrylate group G1 and at least one ethylenically unsaturated polymerizable functional group G2 different from the group G1; 
 0-55 wt % of one or more polymerizable compounds B selected from the group consisting of difunctional acrylates; and 
 0-55 wt % of one or more polymerizable compounds C selected from the group consisting of trifunctional acrylates, tetrafunctional acrylates, pentafunctional acrylates, and hexafunctional acrylates; wherein 
 all weight percentages of A, B, and C are based upon a total weight of the polymerizable composition; 
 at least one polymerizable compound B or C is present in the polymerizable composition; and 
 the polymerizable compound A has a copolymerization ratio of
   0.002< r   2   /r   1 <0.200 
 
  with r 1  and r 2  representing copolymerization parameters of methyl-G1 and methyl-G2, respectively, determined according to a method of Kelen-Tudos if the combination of G1 and G2 is not listed in the following Table: 
 
       
         
           
                 
                 
                 
                 
                 
               
                   TABLE 
                 
                     
                 
                     
                   G1-group 
                   G2-group 
                   r1 
                   r2 
                 
                     
                 
                     
                 
                 
                 
                 
                 
                 
               
                     
                   acrylate 
                   allylether 
                   11.0 
                   0.04 
                 
                     
                   acrylate 
                   allylester 
                   11.0 
                   0.04 
                 
                     
                   acrylate 
                   allylcarbonate 
                   10.2 
                   0.04 
                 
                     
                   acrylate 
                   vinylether 
                   3.6 
                   0.02 
                 
                     
                   acrylate 
                   vinylester 
                   3.5 
                   0.02 
                 
                     
                   acrylate 
                   vinylcarbonate 
                   3.5 
                   0.02 
                 
                     
                   acrylate 
                   fumarate 
                   1.9 
                   0.09 
                 
                     
                   acrylate 
                   maleate 
                   1.9 
                   0.09. 
                 
                     
                 
             
                
                
                
                
               
               
                
               
            
             
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
       2. The free radical curable liquid according to  claim 1 , wherein an amount of polymerizable compounds in the polymerizable composition different from the polymerizable compounds A, B, and C is smaller than 5 wt % based upon the total weight of the polymerizable composition. 
     
     
       3. The free radical curable liquid according to  claim 2 , wherein the compound A is represented by the Formula (I): 
       
         
           
           
               
               
           
         
         wherein 
         GX and GY are independently selected from the group consisting of G1 and G2; 
         n and m are independently selected integers having a value of 0 or 1; and 
         L represents a (n+m+2)-valent linking group including at least one carbon atom. 
       
     
     
       4. The free radical curable liquid according to  claim 3 , wherein the integers n and m both have a value equal to 0. 
     
     
       5. The free radical curable liquid according to  claim 4 , wherein a molecular weight of compound A is smaller than 800 Dalton. 
     
     
       6. The free radical curable liquid according to  claim 5 , wherein the polymerizable functional group G2 is a vinyl ether group. 
     
     
       7. A free radical curable ink for inkjet printing, the free radical curable ink comprising:
 a colorant; and 
 the free radical curable liquid according to  claim 6 . 
 
     
     
       8. A free radical curable ink for inkjet printing, the free radical curable ink comprising:
 a colorant; and 
 the free radical curable liquid according to  claim 1 . 
 
     
     
       9. A UV-curable pigment inkjet ink set including a free radical curable ink for inkjet printing according to  claim 7 . 
     
     
       10. An inkjet printing system comprising:
 the free radical curable ink according to  claim 7  in a piezoelectric print head. 
 
     
     
       11. A packaging material for packaging food comprising:
 a cured layer of the free radical curable ink according to  claim 7 . 
 
     
     
       12. A free radical curable liquid for use in printing, the free radical curable liquid comprising:
 one or more initiators selected from the group consisting of polymeric initiators and polymerizable initiators; 
 a polymerizable composition consisting essentially of: 
 25-98 wt % of one or more polymerizable compounds A including at least one acrylate group G1 and at least one ethylenically unsaturated polymerizable functional group G2 different from the group G1; 
 0-55 wt % of one or more polymerizable compounds B selected from the group consisting of difunctional acrylates; and 
 0-55 wt % of one or more polymerizable compounds C selected from the group consisting of trifunctional acrylates, tetrafunctional acrylates, pentafunctional acrylates, and hexafunctional acrylates; wherein 
 all weight percentages of A, B, and C are based upon a total weight of the polymerizable composition; 
 at least one polymerizable compound B or C is present in the polymerizable composition; and 
 the polymerizable compound A includes 2-(vinyloxyethoxy)ethyl acrylate or an allyl ester acrylate according to Formula PC-1: 
 
       
         
           
           
               
               
           
         
       
     
     
       13. The free radical curable liquid according to  claim 12 , wherein an amount of polymerizable compounds in the polymerizable composition different from the polymerizable compounds A, B, and C is smaller than 5 wt % based upon the total weight of the polymerizable composition. 
     
     
       14. The free radical curable liquid according to  claim 12 , comprising a compound B selected from the group consisting of alkoxylated cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxane glycol diacrylate, dioxane glycol diacrylate, cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, bisphenol A EO (ethylene oxide) adduct diacrylate, bisphenol A PO (propylene oxide) adduct diacrylate, hydroxypivalate neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethyloltricyclodecane diacrylate, and polytetramethylene glycol diacrylate. 
     
     
       15. The free radical curable liquid according to  claim 13 , comprising a compound B selected from the group consisting of alkoxylated cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxane glycol diacrylate, dioxane glycol diacrylate, cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, bisphenol A EO (ethylene oxide) adduct diacrylate, bisphenol A PO (propylene oxide) adduct diacrylate, hydroxypivalate neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethyloltricyclodecane diacrylate and polytetramethylene glycol diacrylate. 
     
     
       16. The free radical curable liquid according to  claim 14 , further comprising a polymerizable co-initiator and/or a polymerizable inhibitor. 
     
     
       17. A free radical curable ink for inkjet printing, the free radical curable ink comprising:
 a colorant; and 
 the free radical curable liquid according to  claim 14 . 
 
     
     
       18. A free radical curable ink for inkjet printing, the free radical curable ink comprising:
 a colorant; and 
 the free radical curable liquid according to  claim 15 . 
 
     
     
       19. A UV-curable pigment inkjet ink set including a free radical curable ink for inkjet printing according to  claim 17 . 
     
     
       20. An inkjet printing system comprising:
 the free radical curable ink according to  claim 17  in a piezoelectric print head. 
 
     
     
       21. A packaging material for packaging food comprising:
 a cured layer of the free radical curable ink according to  claim 17 . 
 
     
     
       22. A printing method comprising the steps of:
 providing the free radical curable liquid as defined by  claim 12 ; and 
 applying a layer of the free radical curable liquid on a substrate; wherein 
 the layer is applied by: 
 a printing technique selected from the group consisting of inkjet printing, flexographic printing, offset printing, and screen printing; or 
 a coating technique selected from the group consisting of dip coating, knife coating, extrusion coating, spin coating, slide hopper coating, and curtain coating. 
 
     
     
       23. The printing method according to  claim 22 , wherein the layer includes a pigment. 
     
     
       24. The printing method according to  claim 22 , wherein the layer is a white layer including a titanium dioxide pigment. 
     
     
       25. The printing method according to  claim 22 , wherein the layer is a colourless layer present as an outermost layer. 
     
     
       26. The printing method according to  claim 22 , wherein the layer is a colourless layer present as a primer. 
     
     
       27. The printing method according to  claim 22 , wherein the layer is applied by inkjet printing. 
     
     
       28. The printing method according to  claim 22 , wherein the printing method is a single pass printing process using page wide inkjet printing heads or multiple staggered inkjet printing heads which cover an entire width of the substrate. 
     
     
       29. The printing method according to  claim 22 , further comprising curing the free radical curable liquid by exposure to actinic radiation from an ultraviolet LED.